how the mighty fall
by cocoartist
Summary: Old dark magic dictates that the Blacks must have an heir. [AU from the end of OotP] Complete.


for frwllfrnknstn

 **The first section of text is JK Rowling's. There is also a chunk from Dona Tartt's _The Secret History_. Both italicised. Obviously I don't own either of these great works. **

* * *

_._

 _There was a loud bang and a yell from behind the dais. Harry saw Kingsley hit the ground yelling in pain: Bellatrix Lestrange turned tail and ran as Dumbledore whipped around. He aimed a spell at her but she deflected it; she was halfway up the steps now_

 _"Harry - no!" cried Lupin, but Harry had already ripped his arm from Lupin's slackened grip._

 _"SHE KILLED SIRIUS!" bellowed Harry. "SHE KILLED HIM I'LL KILL HER!"_

 _And he was off, scrambling up the stone benches; people were shouting behind him but he did not care. The hem of Bellatrix's robes whipped out of sight ahead and they were back in the room where the brains were swimming…_

 _._

 _._

Had they stayed, all but Neville Longbottom, they'd have seen a body hurled out of the Veil, moments after Sirius Black had fallen through.

A body that, for a moment, looked just like the man who'd fallen through. A body perhaps twenty years younger.

Neville ran forward, as the body began to spasm and choke, and then, to his shock, the man - boy - heaved up gallons of water.

"Longbottom?" the man muttered, and then he passed out.

.

.

.

 _Dark magic_ , they said. _The Blacks must have an heir - it's in their grimoire. Horrific thing._

The man stayed unconscious for days, hidden away in Grimmauld Place; half-aware at times before drifting back into unconsciousness.

(Even Dumbledore had been shocked).

"K-Kreacher?" he called upon waking.

The old elf was beside himself.

"Master?" he gasped. "Master Regulus is awake?"

The boy smiled, his face pale and eyes still closed.

"Did you destroy it?"

"Destroy what, Regulus?" another voice interrupted.

"The locket," he said hoarsely, pulling himself up frantically, grey eyes flashing open. "Did it work?"

"I think," Albus Dumbledore said gently, "that you and I have much to discuss."

He handed the Regulus a potion. The boy - man, perhaps, now - scowled at it.

"What is it?" he asked, sniffing suspiciously. "Where am I?"

He gazed around the familiar room in surprise.

 _Home_.

"Why are _you_ here?" he amended.

"You have been… gone for a long time," the old man replied. "It's an Invigoration Draught. Drink up."

Regulus drank, and then he told his old Headmaster everything. And in return, Albus Dumbledore told him a horrific tale of war and murder and Horcruxes.

.

.

(His arm was clean).

.

,

Weeks passed and he was hidden away, even from the Order for all that they used his house as their own.

Potter's house, they said, but Kreacher answered only to him. The family magic superseded a written Will from a disowned bloodtraitor; the house was his.

 _You killed my brother_ , he said to the elf. _It was not well done._

But he understood. Sirius had never been kind to him.

The goblin came, brought by Dumbledore, to formally hand over the unclaimed Black vaults. He'd never been proven to be dead, they told him. Goblins required proof.

A home and money. But not freedom. Not that until the end of the war.

.

.

.

The first time he met the Mudblood was the night he was introduced to some of the Order. Lupin, Moody, Tonks and Shacklebolt. No one else.

He was fully recovered, Dumbledore said.

 _(Don't mention the Horcruxes._

 _We will find them and destroy them. But you cannot be seen by Voldemort… his obsession with immortality would make you a greater target than even Harry)._

His mission; six times greater than he'd believed.

Harry was not to see him, Dumbledore told them. Or even know. If Voldemort saw Regulus Black, looking no older than the day he died, there would be too many questions.

The boy who'd found him (the son, rather than the father as he'd initially believed) had been sworn to secrecy.

"Why am I here, Headmaster?" the Mudblood asked. She was hardly more than a girl, and Regulus had to agree with the question.

"Miss Granger, I have need of your extraordinary mind… Regulus will help me find the Horcruxes. You will find out how to destroy them."

She looked flabbergasted, as well she might.

.

.

It took her less than a month, in the end.

"Fiendfyre or basilisk venom," she told the headmaster. "I was thinking - the sword is goblin-made isn't it? So it only takes on what makes it stronger… it would be the safest, I think. Or we could go into the Chamber, but then we'd have to tell Harry…"

Regulus watched Dumbledore's face light up.

Grudgingly, once it was explained to him, he couldn't fault her plan. How simple, how elegant to use a sword already prepped with venom. A sword that happened to be in the Headmaster's possession.

"What you did… It was very brave," she said to him, one night. She'd come specifically to see him. It was uncomfortable. "Professor Dumbledore told me… he said the ring was cursed. He'd be dead, if it wasn't for you."

She was so proper. That's what annoyed him the most. He could see her ferocious brilliance. He'd watched her calmly read through the darkest, most evil books in the Black's library without flinching. She'd found a quick and easy solution to the Horcrux problem - a problem that Kreacher hadn't solved with years to think about it and a direct order from his Master. She'd been at the battle when he'd been returned, fighting the likes of Malfoy and Nott… She sat there, in his Library, her shirt impeccably pressed, legs (long long legs, he'd noticed the day she'd worn a fucking skirt and -) in hideous Muggle jeans and yet…

She carried herself like Pureblood. Regulus had never really spoken to a Muggleborn before; there had been some in his year at Hogwarts of course, but they'd all had hideous accents like Severus's before it had magically disappeared over the summer at the end of Regulus's first year. Cresswell had been one of Slughorn's favourites, he recalled. Had some stupid first name like Dagger. But _this_ girl - she wasn't like that fool.

She was kind to the elf, in the face of what even Regulus considered beyond the pale rudeness. But _graciously_ kind, kind as though she recognised that Kreacher knew no better.

(And if he, Regulus, had told the elf to stop being rude to her, well that was something he'd worry about later).

"Thank you," he replied, grudgingly.

Saving the man he'd always seen as a Muggle-loving freak had tasted sour… but if he could stop the Dark Lord it would be worth it.

"Why did you turn?" she asked, and he wondered how long his question had burned at her. She was as curious as a cat about anything intellectual - not that he'd noticed, no, it was just obvious - but it had been almost two months since his return, two months since they'd been working together in secret.

He thought about the question.

Because there's a line, even with Dark Magic, that you can never cross.

Because I believed in a man's promises and found his goals were far different.

Because I was offered the world and would have been given nothing.

"It's complicated," he said, eventually.

"Try me," she challenged and he watched how her hair sparked and thought -

no, _understood_ , that she was magical, truly and inherently magical.

"It wasn't for people like you. I still believed Mudbloods were lesser. But there's a line between wanting power and doing something evil. Horcruxes - I grew up with what people like to call Dark Magic, but not like that. What you have to do… only madman would survive. And, I suppose, that's what I saw. I joined him because he offered me the world. But really, he only wanted it for himself. He didn't care about our goals, what we wanted. He just wanted power and he'd found a way to get it."

"So you still believe I'm less than you?" she asked, and he cringed at the disgust in her voice. How could she despise him? It went against everything he'd ever believed and yet…

"You, no. I still believe the Muggle world is a threat to us but… I don't want to rule it any more. I just want my world to be safe."

She was quiet for a while, just watching him and he felt uncomfortable under her gaze, as though she could see through to something inside him, something cowardly and small and selfish.

She checked her watch with an elegant twist of her wrist.

"I need to go," she told him. "I won't see you before Hogwarts now; I'll be at the Weasley's for the rest of the summer. I brought you some reading… these," she gestured at his family's bookshelves, "probably aren't the best companion for a confused and lonely man walking the line between doing the right thing and going back to the wrong."

He scowled at her words. She opened the bag she'd brought with her and pulled out a pile of books.

 _Muggle_ books.

"I think you'll find them enlightening. Goodbye Regulus."

.

.

.

He hadn't intended to, but eventually the loneliness of Grimmauld Place with only Kreacher, and occasionally the werewolf and the damn Aurors for what might loosely be termed company, he read the books she'd left.

 _"Once, over dinner, Henry was quite startled to learn from me than men had walked on the moon. "No," he said, putting down his fork._

 _"It's true," chorused the rest, who had somehow managed to pick this up along the way._

 _"I don't believe it."_

 _"I saw it," said Bunny. "It was on television."_

 _"How did they get there? When did this happen?""_

Regulus, too, was shocked to learn this. He wondered if it was true; wondered at the power of the book, at how the writer seemed to understand him, understand his soul and yet there was no magic. Did that mean Muggles were not so very different?

(Had they _really_ gone to the moon?)

Eventually, with no other way to find out, he wrote to her.

.

.

 _Yes,_ she wrote. _It's quite true. I'm glad you enjoyed_ The Secret History. _Here are some newspaper articles about the moon. I have ordered you a Muggle encyclopaedia. It will probably be delivered to one of the houses next door, as it's coming through the Muggle post so you'll have to work out how to go and get it. Introducing yourself to your neighbours and asking if anything's been delivered (perhaps you live at 12 Grimmauld 'Street'?) there might be rather more civilised than sneaking in._

.

.

He tried it. The Muggles were nice. Invited him him and pushed a glass of wine into his hand. The house was bohemian. _Artists_ , they explained, smiling.

 _Would you sit for us? Ever such a beautiful face hasn't he, Dorothy?_

 _Not today,_ he excused.

 _Well come back, drop in any time._

.

.

The encyclopaedia was -

was

\- beyond anything - _anything_ \- he could ever have imagined.

B for bomb he read in horror. H for Holocaust. M for Martin Luther King. P for physics.

There were nineteen books of it. He hardly slept for days on end, tumbling over each other with the pages.

.

.

He emerged from the other side of a pile of novels and an encyclopaedia anew.

.

 _You have opened my eyes without taking me even outside my house, Hermione. What magic is this? It is as though I have been shattered and unravelled - I am broken._

 _Everything I believed is a lie and now I have no foundations._

 _Forgive me._

.

She wrote back, asking him for advice about house-elves. _You are the only one who really understands, and perhaps now you've read about slavery and subjugation you'll understand there has to be another way. It's wrong, but I don't know how to explain it._

 _._

 _._

 _Hermione, house elves are what used to be called brownies. You can't rip them away from their homes and families. What you can do is talk to them, find out if there's ways to ensure they're being treated well. Perhaps, in time, you can introduce payment, but I'd say the first step would be educating them, as you have with me. Most elves can't even read. Give them the tools to change their own fate._

.

.

S _ign your name as Viktor_ , she told him once. _That's who people think I'm writing to._

Who the hell is Viktor? he wanted to write back, furious, but did not. That would be too close to revealing something he could hardly acknowledge even to himself.

.

.

.

She visited again, on New Year's Eve, and he could see some change within her, as though she'd been hurt, behind her bright-eyes and tanned skin.

"Skiing," she explained. "My parents go every year, they've got a chalet in Chamonix. I came back early, though."

They shared a bottle of champagne from his father's cellar, and Regulus almost worked up the courage to kiss her. But she didn't invite him to, and took a taxi home not long after midnight. Her parents' house was close by; also in Islington.

"I'll come back tomorrow with more books," she promised. "Now I can use magic I'll be able to bring more."

.

He asked, eventually, why she was not with her friends.

"I've fallen out with one of them. Ron. Harry is staying with his family so…"

He frowned.

"Why did you fall out?" he pressed, and to his immense irritation she flushed.

"None of your business," she said, shortly.

He took a deep breath.

"Alright. Sorry. Anyway, back to the potions issue, I think you need to think about the theory you've learned and apply it more to the practice. A friend of mine at school taught me. So the book is a basic guide, right? But then you've got to think - is there a better, more efficient way? And also stuff like… you know, little things… the lunar cycle, for instance, or even the time of day."

She came every day, and even Flooed back to Hogwarts from his fireplace. Her smiles and sharp intellect lifted his spirits.

He missed her, when she went back.

.

.

.

 _I've got to go to Ron's brother's wedding. Would you like to come with me? I've asked Dumbledore and he says it's fine as long as you're disguised._

 _._

 _._

 _._

"You knew, didn't you?" he asked her, as they lay wrapped together in his bed at Grimmauld Place, her dress crumpled from emergency apparition. "You knew they'd attack?"

"I had a feeling they might. I just… I wanted you there with me. I'm sorry Harry and Ron were so cross. They'll have cooled down by tomorrow."

He kissed her, for the second time that night (the first had been on the dance floor, not long after he'd been introduced to the real Viktor).

A Muggleborn witch in his bed, he thought. How his mother would have screeched. The thought gave him no pleasure; for all her faults - and he could see that they were, now - she'd loved him fiercely.

.

.

.

It was all over before September in the end. Harry Potter, who was a braver man than Regulus could ever aspire to be, had spent hours closed up with Dumbledore in Sirius's old room the day after the fiasco that had been the Weasley boy's wedding, and he'd come out, pale faced but accepting.

"I understand why you didn't tell me," Regulus overheard him tell Hermione. "About the Horcruxes… about Regulus."

He didn't, it had to be said, actually _apologise_ for the way he'd spoken to Hermione but she seemed to understand and there was some sort of appallingly Gryffindorish scene where she cried and Harry almost cried and Regulus, who'd merely been going to ask them down to dinner, ran away and told Kreacher to put a stasis charm on the food.

The next day Harry Potter left the house, alone. He returned pale and sad and tired but victorious.

.

.

.

"I love you," he told her, two years later and she turned to him, startled.

"I know," she said fondly. "Did it really take you this long to work it out?"

* * *

It's been too long since I wrote Regulus Black.

Let me know what you thought.


End file.
